Mojo JS bindings: introduce concepts that are more similar to C++ bindings:

mojo/public/tools/bindings/generators/js_templates/interface_definition.tmpl

Index: mojo/public/tools/bindings/generators/js_templates/interface_definition.tmpl
diff --git a/mojo/public/tools/bindings/generators/js_templates/interface_definition.tmpl b/mojo/public/tools/bindings/generators/js_templates/interface_definition.tmpl
index 1b5cafa01e4501e67a3e9694bdb55d818a98513e..9ae211659b890555de2057ac2a635110792fa2ff 100644
--- a/mojo/public/tools/bindings/generators/js_templates/interface_definition.tmpl
+++ b/mojo/public/tools/bindings/generators/js_templates/interface_definition.tmpl
@@ -2,12 +2,23 @@
   var k{{interface.name}}_{{method.name}}_Name = {{method.ordinal}};
 {%- endfor %}
 
+  function {{interface.name}}Ptr() {

[yzshen1, 2016/12/02 00:22:59]

As you can see, I decided to create FooPtr which is a subclass of
InterfacePtrBase. The benefits are:
- shorter name when creating an interface pointer;
- both generic InterfacePtrBase methods and mojom interface methods are directly
exposed by FooPtr;
- if there is name collision between generic InterfacePtrBase methods and mojom
interface methods, people still can use something like
  InterfacePtrBase.prototype.isBound.call(obj)
to call the hidden methods. And we could provide syntax sugar for that, such as
ToInterfacePtrBase(obj).isBound().

One thing should be noted is that with this approach, we will eventually need a
FooAssociatedPtr subclass as well. I think code bloat shouldn't be an issue
given that eventually we will compile our generated JS code.

WDYT?

+    bindings.InterfacePtrBase.call(this, {{interface.name}});
+  }
+  {{interface.name}}Ptr.prototype =
+      Object.create(bindings.InterfacePtrBase.prototype);
+
   function {{interface.name}}Proxy(receiver) {
     bindings.ProxyBase.call(this, receiver);
   }
   {{interface.name}}Proxy.prototype = Object.create(bindings.ProxyBase.prototype);
 
 {%- for method in interface.methods %}
+  {{interface.name}}Ptr.prototype.{{method.name|stylize_method}} = function() {
+    return {{interface.name}}Proxy.prototype.{{method.name|stylize_method}}
+        .apply(this.connection.remote, arguments);
+  };
+
   {{interface.name}}Proxy.prototype.{{method.name|stylize_method}} = function(
 {%- for parameter in method.parameters -%}
 {{parameter.name}}{% if not loop.last %}, {% endif %}